#!/bin/sh
#
# This script generates a project-wide version identifier for use by
# the `elftc_version()' API.
#
# $Id: make-toolchain-version 3731 2019-04-06 14:28:34Z jkoshy $

#
# Defaults.
#
buildhost=`uname -s`
elftcname="elftoolchain"
options="e:h:o:r:t:"
top=""
version="HEAD"
versionfile="elftc_version.c"
progname=`basename ${0}`

usage()
{
    exec >&2

    # Print a message, if supplied.
    if [ -n "${*}" ]; then echo "##${@}"; fi

    echo "Usage: ${progname} [options]"
    echo "	Generate a toolchain-wide version number"
    echo "	-e PROJECTNAME Set the project name [default: ${elftcname}]."
    echo "	-h HOSTOS      Set the build OS [default: ${buildhost}]."
    echo "	-o OUTPUT      Set the output file [default: ${versionfile}]."
    echo "	-r VERSION     Set the version string [default: ${version}]."
    echo "	-t TOPDIR      Set the top-of-tree directory [required]."
    exit 1
}

# Determine the revision number for the source tree.
#
# - If CVS is detected, we use the string `unknown'.
# - If SVN is detected, we use the `svninfo' tool to determine the
#   in-tree revision number.
# - Otherwise, we use `git --describe'.
get_revision_string()
{
    v="unknown:unknown"
    if [ -d CVS ]; then     # Look for CVS (NetBSD).
        v="cvs:unknown"
    elif [ -d .svn ]; then  # An SVN checkout (SourceForge or FreeBSD).
        svnversion="$(svnversion 2>/dev/null)"
        if [ -n "${svnversion}" ]; then
            v="svn:${svnversion}"
        fi
    else        # Try git (DragonflyBSD).
        gitversion="$(git describe --all --dirty --long 2> /dev/null)"
        if [ -n "${gitversion}" ]; then
            v="git:${gitversion}"
	fi
    fi

    echo "${v}"
}

#
# Parse options.
#

while getopts ${options} option
do
    case ${option} in
	'e') elftcname="${OPTARG}"   ;;
	'h') buildhost="${OPTARG}"   ;;
	'o') versionfile="${OPTARG}" ;;
	'r') version="${OPTARG}"      ;;
	't') top="${OPTARG}"         ;;
	'?') usage                   ;;
    esac
done

[ -n "${top}" ] || usage

curdir=`pwd`
cd ${top} || usage "ERROR: Cannot change directory to \"${top}\"."

# Determine the in-tree revision number.
versionstring="$(get_revision_string)" || {
    echo "ERROR: cannot determine a revision number." 1>&2;
    exit 1
}

cd ${curdir} || usage "Cannot change back to ${curdir}."

#
# Only replace the source file if its content has changed.
#
tmpfile=`mktemp ${TMPDIR:-/tmp}/MV.XXXXXXX`
trap "rm -f ${tmpfile};" 0 1 2 3 15

cat > ${tmpfile} <<EOF
/* WARNING: Generated by "${progname}". */

#include <sys/types.h>
#include <libelftc.h>

const char *
elftc_version(void)
{
	return "${elftcname} ${version} ${buildhost} ${versionstring}";
}
EOF

if ! cmp -s ${tmpfile} ${versionfile}; then
    echo "@ ${progname}: building \"${versionfile}\"."
    cp ${tmpfile} ${versionfile} || exit ${?}
fi
